Method and means for mechanically treating metal foils



Jul 16, 1940.

METHOD AND MEANS FOR MECHANICALLY TREATING METAL FOILS Filed Nov. 12, 1956 3 Sheets-Sheet 1 INVENTOR. Sfrefflu-d B 4 4 ATTORNEY.

8. B. ALLEN 2 ,207,995

S. B. ALLEN METHOD AND MEANS FOR MEC HANICALLY TREATING METAL FOILS Jul 16, 1940.

3 Sheets-Sheet 2 Filed NOV. 12, 1936 IN VENTOR. Qf/J .3 fll/el; BY 4/ July 16, 1940. s, ALLEN I I 2,207,995

METHOD AND MEANS FOR MECHANICALLY TREATING METAL FOILS Filed Nov. 12, 1956 s, Shee ts-Sheet a ATTORNEY.

Patented July 16, 1940 METHOD AND LIEANS FOR MECHANICALLY TREATING METAL FOILS Stratford B. Allen, Arlington, Mass., assignor to Tobe Deutschmann Corporation, Canton,

Mass.

Application November 12, 1936, Serial No. 110,492

1 Claim.

1 The presentinvention relates to a method and apparatus for treating foil, such as aluminum or other metal foils, and also for the treatment of thin sheets of any'type of material, that is wound in rolls or comes in long strips. More particularly the invention relates to apparatus for mechanicallyroughing smooth metal foil such as aluminum, copper, tin or foils of other metals,. and in particular for the preparation of aluminum foils in the manufacture of electrolytic condensers. Y

Up to the present time the common practice has been to treat by certain chemical processes aluminum foils of a similar nature that are used in the manufacture of electrolytic condensers to provide a more porous surface in order to enlarge the area upon which the electrolytic film might form. In this treatment the foil is passed through a so-calledetching bath which chemically attacks the foil and eats away the surface in spots making it rough and porous in order to provide a large surface area uponwhich the electrolytic film forms. "The chief diiiiculty with the chemical process is that the foil is not always uniform and oftentimes more of the surface is etched away than is really desirable. Due to the char 'acter of the foil itself some-parts of it that may originally have a more highly polished surface than the rest or that may be of slightly different characteristics than the rest, may not be chemi- 'cally acted upon to thesame extent that other partsof the foil is, with the result that unless theprocess is carefully observed, the foil may not be uniformly treated;

In addition to this may oftentimes combine with certain impurities in the foil itself, oractually form with the foil certain compounds that may be injurious to the article when actually completed.

'By means of the present invention aluminum foil is mechanically treatedin such a manner that no chemical action is necessary, and as a result therefore, the foil after treatment iscompleted still remains pure aluminum foil prepared to receive its proper process in the manufacture of electrolytic condensers. It has also been found that with the present method and apparatus, the foil is treated very uniformly and slightirregularities do not preventa uniform result from being obtained in the treatment. While the present foil after treatment may be called a'mechanically etched-foil, nevertheless, it more properly is'a mechanically prepared foil to provide an'increased surface area and to make it moreready to receive the chemical treatment in the preparation of electrolytic condensers.

In the present invention the novelty not only resides in the foil itself, but in the method and apparatus used in its preparation. The foil treatedin the present invention usually comes in the chemicals, and acids in'itself andwill easily tear and also because the area of the surface that must be treated is so tremendous that any mechanical means must necessarily move rapidly over its surface. In the present invention the method and apparatus is such that both of these difiiculties have been overcome, and it is possible to treat metal foil of quite flimsy character in such a uniform mannerthat electrolytic condensers made from it will be uniform and possess the definite predetermined characteristics that are desired. The method will be more fully described in connection with the apparatus and also forming a part of the present invention. In the parts used in the present invention the metal foil is treated in a continuous process. the metal being unwound at one end of the machine and wound up again in a complete roll at the other end of the machine in such a manner ,that the foil is ready for processing in the manufacture of electrolytic condensers or for other purposes for which the foil may be used The present invention will be more fully described in connection with the drawings showing an embodiment of the same, in which Figure 1 shows a perspective of the front end of the machine where the treatment commences.

Figure 2 shows a rearpart of the machine where the washing and rewinding occurs. Figure 3 shows a detail of the means used for guiding the foil.

Figure 4 shows'an enlarged view of one end of the grinding rolls.

Figure 5 shows a sectional view of a chuck member in which the grindingrroll fits.

Figure -6 shows a section on the line B-B' of 7 Figure 5.

Figure 7 shows an end View of the spindle mechanism for wi'nding'the roll, and

Figure 8' shows a section on the line i i- A of Figure '7.

In Figure l, the roll not shown provides a strip which fits to the machine beneath the lower-roll {and the upper roll 3 passing over the upper roll as indicated by the strip l on this roll. The strip then p'asses downward into. a tank 4 which is filled with an abrasive compound iwhich will be described later. Inside of the tank 4 ispositioned a roller 6 fitted into the sides of the tank so as to allow it to roll freely. The

strip l is passed beneath the roller 6 as indicated by the-dotted lines and comes upward in the back of the tank.v The tank 4 may be supported in the frame I by meansof ears 8 extending from either side of the tank through which the rod 9 may pass, which itself is supported in the frame 1, the frame I comprisingthe two angle elements as indicated with suitable cross supports.

The strip I coming upward from the tank, passes be adjusted in tension against each other. Afteremerging between the rollers I7 and E8, the strip passes over the roller I9 and descends downward into the washing tank indicated more clearly in Figure 2. The mechanism in Figure l is described and operated as follows.

The rollers l2, 13, I4, and I5 are provided with split shafts, one end of which is mounted in the bearings 26, 2I, 22 and 23 in the side plate 24, while the other end may be similarly mounted in the plate 25. As indicated in Figure 1, the rollers I2 and 54 at the right end pass through a plate 29 to the right of which is 'a collar 21 upon which the rolls 28 and 29 are mounted, while the shafts I2 and M are free to turn in the plate 26. The plate 25 is locked to these shafts for longitudinal motion, on the right by the collar 21 and on the left by a similar collar which is shown at the other side of the figure by the number 30. The pulleys 28 and 29 are operated through the belt 3! which is connected to a suitable motor drive. The plate 26 is pinned by a pivot 32 to the link 33 which is pivoted at its other end to one end of a bell-crank lever 34 as shown at 35.

The bell-crank lever 34 is pivoted by means of the pivot 38 to the block 3! mounted on the frame I. The other end of the bell-crank lever is attached by means of the forked pivot 38 to the crank arm 39 by means of the joint 40, which at its lower end is slotted to receive the flange 4| of the crank 39 and through which the pivot 42 passes. The crank 35} is driven by the eccentric 43 which may be operated through a suitable motor from the shaft 34; A similar arrangement is provided for the shafts I3 and I5 and the two groups may be so geared up that they work in opposite directions. This may be easily done by driving the two bell-crank levers 34 and 49 from the crank arms at opposite ends of the shaft 44, these crank arms being set 180'out of phase to produce motion simultaneously in opposite directions.

In the operation of the system, the strip I picks up a certain amount of abrasive from the bath 5. This abrasive may comprise fused aluminum. oxide, commonly known as Alundum in a mixture of ethylene glycol with a small amount of gum arabic to increase the jell of the mixture so as to provide a firmer resistance for working upon the strip. While the strip 3 may be rotated 'quite rapidly, the rolls I2 and i4 and I3 and I 5, move very rapidly longitudinally back and forth. The rolls themselves may be made of Alundum grindstone or Carhorundum, or some other very hard abrasive surface. The abrasive mixture picked up' by the path is retained and acted upon by the rolls themselves so that an intimate rubbing is obtained against the strip without a very great pressure being applied. In addition to this, the abrasive action is uniform over the whole surface so that the surface cannot tear. The rolls I! and I8 which act principally as wiping rolls After passing through are held against one another by means of the bearing supports v45 and 46whichi may be tensioned to each other by means of the wing nuts 4! and 48 for suitable and desired tension. After the strip has passed over the abrasive end of the device, it comesdown into a washing tank 583 which is provided with a roll 5| similar to the roll 6. The tank 50 issupported by ears 52, 52, bymeans of the shaft 53 mounted on the angles 54 of the frame 55.

After the strip I has come out of the tank it is further'sprayed by means of the spraying pipes 55, 55, connected to the box 51 which is fed by means of the-hose 58. From the spray tank, the strip passes over the wringing rollers 59, 69, 6! and 62, the latter of which may be so adjusted to wring the strip I' fairly dry, although this process-is fully completed in the arrangement to follow. From the wringing rollers the strip passes over the two driving rollers 63 and 64 in the manner shown. These two rollers 63 and 64 are mounted on-the shafts 65 and 66. re-

spectively, which are supported in the bearings ii? and 68, and are driven in geared relation-by means of the gears 69 and Ill from'the pulley II through the driving system comprising'the shaft 1-2, the pulley I3 and the belt I4. The rollers 63 and 54 furnish the drive over the entire system, drawing the foil over the entire abrasive end of the machine and preparing the foil. for thefinal winding up process.

While the drive may beentiIeIyset at the,

points indicated inFigure 2,'nevertheless, it is also possible to supplement this drive by adrive at a previous point-in the system when the ,two

points are properly adjusted with respect to'each other, so that the speed will be maintained stand-.

ard. The foil after passing between the rollers 53 and 64 and eomingup from the bottom of the lower roller, ascends vertically to the top roll positioned across the top beamlfi... In

the frame beneath the strip I, is positioned a heating lamp 11 which sends-its heat upward in the general direction of g the strip, and .d'riesit as it moves over the top of the frame. The strip i descending in back of the frame, is controlled, 3

by means of the guide lflwhich is shown. in de-, tail in Figure 3. This guide. I8 is. pivoted to the shaft IS in the support of the frame and tends to preserve the alignment of thest-rip as it is" being finally wound up in a roll as indicated at,

t! in the back of the frame. -'I'-he roll IlI .is

wound on a'spindle .82 and tensionedbymeans of a spring tension which ,is shown more in. detail in Figures '7 and 8. This tension is. maintained in such a way that the roll slips, sufficiently .to

wind just enough to keep a uniformtension on I I the strip as it emerges from the driving -rolls:6 3 7 and 54.

This is shown in. detail in Figures 7 and 8.

:Upon the cross beam-83 Figure 2h-is mounted a.

bracket or support 84 which carries the-mechanism for rewinding the foil afterthe-treatment has been completed. A fitting '85, Figure 8, hav ing a long barrel and a flange element is provided with the flange extending outwardly fromthe barrel and bolted tothe support by bolts 86. The barrel fits in the support 84' and is open at. the inner face to receive the sleeve or rod 81 of the thumb screw '85 means threading through-the end of the barrel 85 and into-the sleeve 6? for the purpose presently to be explained;

70' 1 which is adjustable in position in the barrel by A shoulder end collar ;88 is provided 5$ at the end of the rod 81 and this collar extends in the shaft 9|. Two ball bearing fittings 89 and 92 are provided about the collar 88 and the shaft 9| respectively supporting the sprindle 90 in the shoulders 88' and 93. and the spindle is held to the shaft by these fittings and the nut 94 threaded to the end of the shaft 9|.

The spindle 90 is provided with a flange I06 bearing against the face of the pulley I00, which .in turn is pulled against the ball bearing fitting I03. This bears against the spring washer I05 which is positioned between the bearing I03 and the washer I04 resting against the end of the barrel 85. It will readily be seen that by screwing up the thumb screw 05, the tension on the spring washer I05 will be increased and thus the friction of the flange I against the pulley face is similarly increased. This friction is increased to obtain sufiicient tension between the pulley and the spindle to approximately equal the tension on the spindle from the winding and allow sufficient slip in the system so that the foil is wound without exerting too great a strain on it.

In Figures 4 and the means by which the abrasive rolls may be replaced is illustrated. As shown in Figure 4, the roll I2 is provided with a shoulder I01, and an end shaft I08 which is adapted to fit in the chuck collar I 09. The shaft I08 is placed in the hole in the collar I09 and tightened by means of screwing down the collar I09 on the jaw elements I I0, which may be made as illustrated m Figure 6 with three sectional jaws III, H2 and H3, with a clearance between each section as illustrated by II4 which is taken up when the collar I09 is tightened thus gripping the shaft I08 firmly in place. The other end of the chuck is formed with the, shaft H5 passing through the plate as shown in Figure 1. Both ends of the abrasive rolls I2, I3, I4 and I5 are made in the same way, so that they may be disassembled and new abrasive rolls substituted when the old ones become worn. The balancing mechanism for balancing and guiding the foil is illustrated in Figure 3. This comprises a frame H6 rectangular in shape, at the top of which is'a cross guiding plate II'I having a guiding groove II8 formed by the outwardly extending pieces H9 and I20. At the lower end of the frame there is provided an angle element I2I holding a roller I22.

The lower end of the frame has a centrally projecting V support I23 with an insulating strip I23 forming a part to insulate the top part of the frame from the base which is fastened to the external machinery. From the support I23 there extends at right angles a shaft I24, mounted to oscillate freely in the bearing I25 which is a part of the assembly including the collar I26 freely positioned but fixed by set screw I26 on the shaft 19. This latter adjustment allows the frame to be tilted in the proper desired direction to have the guide 5 properly work against the foil.

The frame is therefore quite free to oscillate in the plane of the frame which is at right-angles to the normal travel of the foil. If the foil tends to move one way or the other, the frame will follow it always guiding it however to the lower end which relatively on account of the point of pivot, holds its true position with reference to the roll 8|. The roll 8| is slightly crowned so that the foil centers at the mid-point of the roll. By arrangement the foil is wound in exactly the same manner as it was before being unwound and may be used on any type of wind ing machine in the same manner as it might have been used if it had not been unrolled in the first place. The roll when wound upon the spin-- dle 90 may be removed and a new roll treated. It may be noted that since the driving end is quite near the rewinding spindle, very little foil will be wasted in the process, and since all of the foil has been treated before reaching the rolls 63 and 64, the complete roll will all have been treated when the end of the strip comes out of the driving rolls and the winding will auto-matically continue until the entire roll is wound up; The speed at which the roll may be treated, de pends upon the nature of the treatment desired, the width of the roll, and the relative speeds of oscillation of the grinding of the rolls with reference to the driving speed of the foil over the whole machine.

Initial tension may be placed upon the system by means of the weight I21 sustained as a brake upon the pulley I28 on the shaft I92 of the initial roll 2.

The foil treated in this manner described above as has been stated, is particularly useful in electrolytic condensers and has proved to be superior to the chemical treatment whereby only a heterogeneous roughing of the surface is obtained. the present type of treated foil, not only is the roughing more uniform, but it is sharper and makes possible the attainment of acomparatively large surface area. As far as the method of treatment is concerned, this has been outlined above in the description of the apparatus and in the use of materials. The thickness of foil may on account of the treatment be materially increased showing that the peaks raised by the treatment are substantial as compared with the original foil thickness.

While it has been specified that the liquid used is ethylene glycol and the abrasive material, fused aluminum oxide or fAlundum, it is possible to use other liquid carriers such as glycerin and certain oils, although ethylene glycol appears to stand up longer and allow more active use of the abrasive elements. Instead of Alundum, Carborundum may be used or some material as for instance natural emery. The treatment consists primarily of carrying the liquid abrasive compound over abrasive rolls which move transverse in pairs to the direction of travel of the foil itself, the foil serving as a carrier for the liquid abrasive mixture which is worked against the foil by means of the longitudinal motion of the rolls. It will also be noticed the rolls all turn in the the same direction, but since the foil is on opposite sides of successive rolls, the relative motion of the rolls and foils is such as to balance or cancel any tendency for the grinding rolls to pull the foil through the grinding system.

Having now described my invention, I claim? .A method of preparing aluminum foil for electrolytic condensers which consists in passing the foil through a viscous bath composed of ethylene glycol and an abrasive material mixed therewith allowing the foil to be drawn over a group of abrasive surfaces moving transversely to the foil each in opposite direction to the other whereby the abrasive compound provides the working abrasive on the foil.

STRATFORD B. ALLEN. 

